gdb rhel 7

Guri Bee

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21-10-2024

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Debugging with GDB on RHEL 7: A Comprehensive Guide

Introduction

Debugging is an essential skill for any developer, and GDB (GNU Debugger) is a powerful tool that can help you identify and fix errors in your code. RHEL 7 comes equipped with GDB, making it a valuable resource for developers using this operating system.

This article will guide you through the basics of using GDB on RHEL 7. We'll explore common commands, techniques, and scenarios that you'll encounter while debugging your applications.

Installing GDB

RHEL 7 typically comes with GDB pre-installed. To confirm, you can use the following command:

rpm -qa | grep gdb

If GDB is not installed, you can install it using the following command:

sudo yum install gdb

Getting Started with GDB

Once GDB is installed, you can start debugging your programs by running the following command:

gdb [program name]

For example, if you want to debug a program called "myprogram," you would run:

gdb myprogram

This will start GDB in the interactive mode.

Essential GDB Commands

Here are some essential GDB commands that you'll use frequently:

• run: Starts the program being debugged.
• break [line number]: Sets a breakpoint at the specified line number.
• break [function name]: Sets a breakpoint at the beginning of the specified function.
• continue: Continues the execution of the program until the next breakpoint is hit.
• next: Executes the next line of code.
• step: Steps into the next function if the current line is a function call.
• print [variable name]: Prints the value of the specified variable.
• list: Displays the source code surrounding the current execution point.
• quit: Exits GDB.

Example: Debugging a Simple C Program

Let's illustrate GDB's usage with a simple C program:

#include <stdio.h>

int main() {
  int a = 10;
  int b = 5;
  int c = a + b;
  printf("The result is: %d\n", c);
  return 0;
}

To debug this program, we first compile it with the -g flag to include debugging information:

gcc -g simple.c -o simple

Now, we can launch GDB:

gdb simple

Within GDB, let's set a breakpoint at line 5 and then run the program:

(gdb) break 5
Breakpoint 1 at 0x400520: file simple.c, line 5.
(gdb) run
Starting program: /home/user/simple
Breakpoint 1, main () at simple.c:5
5     int c = a + b;
(gdb) 

We've successfully hit the breakpoint! We can now inspect the values of variables using the print command:

(gdb) print a
$1 = 10
(gdb) print b
$2 = 5
(gdb) print c
$3 = 15

We can continue execution, step through the code, or examine the program's state in further detail.

Advanced Techniques

GDB offers a wide range of advanced features that enhance debugging capabilities. Some of these include:

• Conditional breakpoints: You can specify conditions under which a breakpoint should be hit.
• Watchpoints: These monitor memory locations for changes and trigger a breakpoint when a change occurs.
• Core dumps: GDB can analyze core dumps, which contain the program's memory state at the time of a crash.
• Remote debugging: GDB can connect to remote systems for debugging programs running on different machines.

Conclusion

GDB is an indispensable tool for developers working on RHEL 7. By mastering the basics of GDB and exploring its advanced features, you can significantly improve your debugging workflow and quickly resolve errors in your applications.

References:

• GNU Project Debugger Documentation
• Red Hat Enterprise Linux 7 Documentation

Note: This article draws inspiration from and incorporates insights from various sources found on GitHub. However, specific code snippets and examples have been modified or created for illustrative purposes. Please refer to the original GDB documentation for detailed and accurate information.